1. Field of the Invention
The field of the present invention relates to a load indicator apparatus for suspended wheeled vehicles, and more specifically pertains to a new and improved vehicle overload detection system. This system uses an indicator that utilizes the deflection of the suspension of the vehicle to determine if the maximum allowable axle loading limit has been exceeded.
2. Description of the Prior Art
It is important for operators of various types of passenger and cargo-carrying vehicles to be aware of vehicle overweight (overload) conditions occurring when the critical weight (load) limit is exceeded. Overweight conditions may present safety hazards if they exceed the design limit of the vehicle, or may present legal problems for the operator due to safety regulations, or both.
For example, commercial motor vehicles such as trucks, trailers, and containers-on-chassis must comply with Federal and State regulations with respect to the weight carried over each axle. There are both fines and possible removal from service for offenders exceeding the allowable axle loading.
Load indicators have been employed in the prior art to indicate loading of cargo-carrying vehicles relative to the axle structure. For example, U.S. Pat. No. 3,480,095 to Tuchman sets forth a load indicator structure which uses the relative motion of a railroad car and axle to drive a pointer linkage which indicates the car weight on a graduated scale. The structure in Tuchman provides an instantaneous indication of the specific load condition of the associated axle, but does not provide a simple qualitative indication of whether the maximum load limit has been exceeded. The Tuchman device also does not provide any mechanism by which the device may be re-calibrated for variables such as wear on the suspension system, which will effect the accuracy of the device.
Similarly, U.S. Pat. No. 4,384,628 to Jackson shows an overload detector with structure comprising a plurality of gears and cables, providing an indication of the instantaneous load condition to the operator. The structure in Jackson is relatively complicated, with a high part count, several moving parts, and the attendant reliability problems.
It has been recognized that what is required by the vehicle operator in most cases is a direct "Pass/Fail" indication of an overload condition, rather than a quantitative measure of vehicle weight. For example, U.S. Pat. No. 5,376,760 to Horsley describes an electric switch structure in association with the frame and leaf spring suspension structure of a truck. The signal resulting from activation of the switch provides an indication that the load condition associated with that switch has been exceeded. The use of electronics in the Horsley structure makes it susceptible to reliability problems which are not present in purely mechanical structures.
The instant invention overcomes the deficiencies in the prior art by providing for a direct "Pass/Fail" indication of an overload condition with a relatively uncomplicated mechanical indicator.